S, i n both the northern and southern hemispheres, sea levels
.mL~s~ (Ya ^! ~th J A ^^ ^~&,AA.AO <3L CLA --.A o QCX-4 ,
"~ -"Ieclined. .In Florida as the seas retreated, lakes of salt
A
\ water and vast areas of salty ground water were left behind.

With the landscape now exposed to the effects of rainfall,

Sstreamflow and erosion, new layers of sand and clay were

washed down gradient to collect in shallow seas and on the

flatter portions of the land surface. &. js .

Map Eventually the world again turned warm; the glaciers

began to melt; sea. levels rose again and much of the Florida

peninsula was again underwater. Four times the cycle repeated
/
itself; four times the sea rose to cover portions of the land.

Each time it stopped short of the preceding high water mark

but each time it inundated Charlotte County and the southern

tip of the Florida peninsula.

The effect was permanent--if anything connected with
-^
the earth and its geology can be permanent. By the time the

world had moved from the Pleistocene Epoch to the Recent

Epoch, by the time Florida's coastline had stabilized

roughly along its present boundaries, heavy deposits of salt

water had filled the deepest aquifers of Charlotte and

other South Florida counties IThis map shows us the areas

Map in which chlorides (saltS existed in significant quantities

-2-

in the top of the Floridan Aquifer at the end of the

Ice Age. W O Y

lhtil this century---a mere fraction of a second on

a geologic clock---this "problem" was no problem at all.

River Scene There was an abundance of fresh surface water available

and wells drilled into the shallower aquifers produced

a bountiful supply of potable water. So long as the

brackish water remained in the deep aquifers it was harmless. -

But 20th Century man---unaware of the consequences

of his actions, unaware of the various levels of aquifers
Truck Farm
in Charlotte County, unaware of the differences in water

quality in different aquifers and unaware of the causes of

salt water intrusion---upset the system. P o

(y Early settlers in Charlotte County---needing water with

which to irrigate their crops---drilled wells. Observing

5 L.L that, in general, the deeper the well the greater the

artesian pressure, they drilled their wells deep into those

aquifers most contaminated with chlorides, sulfates and

sulfides. Because the artesian pressure was so great,

pumps were unnecessary. Water---thousands of gallons per

day, even millions of gallons per day---poured freely from the

wells into the fields.

Those early settlers had no way of knowing what was

happening inside the well hole beneath the ground. They had

no way of understanding the effect those deep wells were

having upon the equilibrium between the brackish water in the

deeper aquifers and the sea waters in the Gulf and Charlotte

Harbor. They did not realize that they were inviting salt

water encroachment into their ground water resources and, at

the same time, allowing saline and sulfurous water to

contaminate the upper aquifers. They had no way of knowing

that they had set in motion a hydrologic process---actually

two processes---that would eventually contaminate the water

supply of their grandchildren. 7/ / Cl

-3-

Diagram #1 If we look at a cross sectional diagram of Charlotte

.County's geology, the impact of these deep wells upon the

water in the upper aquifers becomes clearer. As in most

parts of Florida, a layer of sand at the surface is under-

lain by a layer of clay. Beneath the clay, a massive strata

of limestone saturated with water extends down several

thousand feet. / /0j

Diagram #2 In Charlotte County, however, unlike most parts of the state,

several layers of clay or other impervious material intersect

the limestone, dividing it into separate aquifers or zones.

There are many local variations, but in general the

deeper the aquifer the greater the chloride and sulfide

contamination. Similarly, the deeper the aquifer the

greater the artesian pressure. /'7 0 ,--/

Diagram #3 When a well is drilled into the lower zones, if it were

properly cased all the way down, the problem with inter-aquifer

contamination would be minimal.

Most wells, however, were cased only down to the upper clay

bed or to the upper zone. Other wells, which were cased to

a greater depth, were cased with black iron and galvanized iron

substances that are attacked by hydrogen sulfide. Thus, over

the decades, these casings became corroded and water flows freely

in and out of the well bore. "

Here is what happens: V

Diagram #4 Water from the deep aquifer spurts up the well shaft. Because

it is under greater pressure than the upper aquifers, water

from the deep aquifer forces its way not only to the surface

but also into the upper aquifers. Thus, it contaminates them "

with greater concentrations of chloride, sulfate, and sulfide.//1

450 If we were talking of only a few such wells the regional
450 + l _/
Contaminated effect would not be particularly significant. However, more
Wells
than 450 such wells have been inventoried in Charlotte CountyA(AI..